Substrate having trim window in a C5 array

Abstract

A substrate 15 has an electrically adjustable trim pad 50 on the bottom side. A circuit pattern 18 resides on the top side, covered by an RF shield 20 . The trim pad is located on the bottom side directly below the RF shield, and is electrically connected 52 to the circuit pattern. A number of surface mount connections 30 , typically C5 solder bumps, are located on the bottom side, and surround the trim pad. The trim pad is trimmed after the RF shield is attached, thus providing more accurate tuning of the circuit on the top side.

What is claimed is:  
     
       1. A C5 substrate having an electrically adjustable trim pad on a bottom side, comprising: 
       a substrate having a top side and a bottom side;  
       a circuit pattern on the top side;  
       a trim pad on the bottom side; and  
       a plurality of surface mount connections on the bottom side, each comprising a C5 solder bump, at least one of the plurality of surface mount connections electrically connected to the circuit pattern on the top side.  
     
     
       2. The C5 substrate as described in claim  1 , wherein a portion of the plurality of surface mount connections surround the trim pad. 
     
     
       3. The C5 substrate as described in claim  1 , wherein one or more of the plurality of surface mount connections is located on the trim pad. 
     
     
       4. The C5 substrate as described in claim  1 , wherein the trim pad is electrically connected to the circuit pattern. 
     
     
       5. The C5 substrate as described in claim  1 , further comprising a mother board, the C5 substrate soldered to the mother board by means of the C5 solder bumps. 
     
     
       6. The C5 substrate as described in claim  1 , further comprising a plurality of trim pads located on the bottom side. 
     
     
       7. The C5 substrate as described in claim  1 , further comprising an RF shield on the top side, the RF shield covering at least a portion of the circuit pattern. 
     
     
       8. The C5 substrate as described in claim  1 , wherein a portion of the trim pad has been removed. 
     
     
       9. The C5 substrate as described in claim  8 , wherein said removed portion is removed after the RF shield is attached. 
     
     
       10. The C5 substrate as described in claim  8 , wherein said removed portion is removed by a laser. 
     
     
       11. A module having an electrically adjustable trim pad on a bottom side, comprising: 
       a substrate having a top side and a bottom side;  
       a circuit pattern on the top side;  
       an RF shield attached to the top side, the RF shield covering at least a portion of the circuit pattern;  
       a trim pad on the bottom side, electrically connected to the circuit pattern, the trim pad located directly below the RF shield;  
       a plurality of surface mount connections on the bottom side, each comprising a C5 solder bump, at least one of the plurality of surface mount connections electrically connected to the circuit pattern on the top side; and  
       at least a portion of the plurality of surface mount connections surrounding the trim pad.  
     
     
       12. The module as described in claim  11 , wherein a portion of the trim pad has been removed. 
     
     
       13. The module as described in claim  12 , wherein said removed portion is removed by a laser. 
     
     
       14. The module as described in claim  12 , wherein said removed portion is removed after the RF shield is attached. 
     
     
       15. The module as described in claim  11 , further comprising a mother board, the substrate is soldered to the mother board by means of the C5 solder bumps.